The present invention generally relates to non-destructive inspection and more particularly, to a method of discriminating kinds of golf balls through utilization of ultrasonic waves.
Commonly, the constructions of golf balls may be broadly divided into two types, i.e., one being the so-called thread-wound golf ball comprising a core portion of round shape, a flexible thread, for example, of rubber tightly wound around said core portion under the application of a tension to a certain extent, and an outer layer, for example, of gutta percha, plastics and the like applied onto said wound flexible thread for covering, and the other being the so-called solid golf ball which is made through one-piece molding, by subjecting to vulcanization during heating under pressure, a mixture including rubber, crosslinking resin, polymerization initiator and filling agent, etc. and filled in a mold. The present invention relates to a method of discriminating or distinguishing between the thread-wound golf balls and solid golf balls as described above.
Conventionally, the solid golf balls have been considered to be suitable only for exercise, but owing to various technical improvements, they have recently undergone a complete change so as to be usable also for actual play. At the present stage, however, the solid golf balls as described above are still inferior to the thread-wound golf balls in any of the important characteristics of golf balls such as shot feeling, resilience, trajectory, etc. Nevertheless, due to the fact that the former are similar in appearance to the latter, there is a possibility of undesirable mixing between the solid golf balls and thread-wound golf balls.
For preventing the mixture as described above, there has been strongly demanded a method of discriminating these golf balls as described above through non-destructive examination. In connection with the above, since golf balls are normally painted white, the appearance thereof is also an important factor as article, and therefore, any method which might give rise to soiling or small flaws, etc. on the surfaces of golf balls in the process of discriminating inspection is not preferable to be adopted.